1. Field of the Invention
The invention relates to a high pressure tank and a manufacturing method of a high pressure tank.
2. Description of Related Art
A variety of high pressure tank structures have been developed (Japanese Patent Application Publication No. 2008-164131 (JP 2008-164131 A), for example). JP 2008-164131 A describes technology that involves forming an adhesive layer between a liner and a fiber-reinforced plastic layer in order to increase an airtight sealing property.
With the high pressure tank described in JP 2008-164131 A, the liner is adhered to the fiber-reinforced plastic layer by an adhesive. Therefore, when the flexibility of the liner decreases at low temperatures, for example, stress from the internal pressure of the tank may concentrate at a localized part of the liner, and the liner may warp.
Also, when the high pressure tank is to be filled with hydrogen gas used in a fuel cell vehicle, hydrogen is continuously released from the high pressure tank at a high rate of flow when the fuel cell vehicle travels at high speeds. At this time, the temperature inside the high pressure tank rapidly drops to a low temperature as a result of the hydrogen inside the high pressure tank adiabatically expanding. For example, in a cold region where the outside air temperature is −10° C., the temperature inside the high pressure tank will drop to an extremely low temperature of approximately −70° C. At this extremely low temperature, breaking elongation of the liner decreases, so with a high pressure tank having a structure in which a liner is adhered to a fiber-reinforced plastic layer by an adhesive, high stress may be applied to a localized part of the liner.